Investigating Data

AIC_COPD <- lm(data = heat_health, annual_COPD_deaths_per100000 ~ urban_level + 
            Median.AQI + Count_ExHeat_Days)

step(AIC_COPD)
## Start:  AIC=2460.45
## annual_COPD_deaths_per100000 ~ urban_level + Median.AQI + Count_ExHeat_Days
## 
##                     Df Sum of Sq    RSS    AIC
## - urban_level        1       4.4 191267 2458.5
## <none>                           191262 2460.4
## - Median.AQI         1    6924.5 198187 2472.6
## - Count_ExHeat_Days  1   18535.0 209797 2495.2
## 
## Step:  AIC=2458.46
## annual_COPD_deaths_per100000 ~ Median.AQI + Count_ExHeat_Days
## 
##                     Df Sum of Sq    RSS    AIC
## <none>                           191267 2458.5
## - Median.AQI         1      7145 198412 2471.0
## - Count_ExHeat_Days  1     19753 211019 2495.5
## 
## Call:
## lm(formula = annual_COPD_deaths_per100000 ~ Median.AQI + Count_ExHeat_Days, 
##     data = heat_health)
## 
## Coefficients:
##       (Intercept)         Median.AQI  Count_ExHeat_Days  
##           56.2588             0.7417            -0.2704
plot(AIC_COPD)